Herpes zoster of the cornea, known as herpes zoster ophthalmicus, is a serious reactivation of the varicella-zoster virus—the same virus that causes chickenpox. After a chickenpox infection, the virus becomes dormant in nerve tissue and can reactivate years later as shingles. When this reactivation affects the nerve supplying the face and eye, it can lead to inflammation and damage to the cornea. This condition is a severe complication of shingles that requires prompt medical evaluation, as delaying treatment can lead to scarring that may permanently affect sight.
The Viral Pathway to the Eye
The virus’s journey to the eye begins long after a chickenpox infection. The virus retreats into the nerve roots, the sensory ganglia, where it remains latent. While for many people the virus never causes problems again, a decline in the body’s immunity, often due to aging, can allow it to reactivate.
Once reactivated, the virus travels along a specific nerve pathway. In cases of herpes zoster ophthalmicus, the virus follows the path of the trigeminal nerve. The ophthalmic branch of this nerve is most commonly involved, providing sensation to the forehead, scalp, and the eye itself.
The virus uses this nerve as a direct route to the surface, emerging in the skin and, in about half of these cases, the structures of the eye. This is why the initial shingles rash appears on the forehead and scalp on one side of the face.
Recognizing Ocular Symptoms
The first indication is often a prodrome, which includes symptoms like fever, headache, and a tingling or painful sensation on one side of the forehead. Following this, a characteristic rash of small, red, and painful blisters appears on the forehead and sometimes the scalp, strictly on one side of the face.
When the eye becomes involved, a new set of symptoms emerges. These can include:
- Significant eye pain, which can be sharp or aching
- Redness of the white part of the eye and swelling of the eyelid
- A pronounced sensitivity to light, known as photophobia
- Vision that has become blurred or hazy
- A persistent feeling that something is in the eye, like sand or grit
A telling diagnostic clue is Hutchinson’s sign, which is the presence of a shingles blister on the tip of the nose. The nasociliary nerve, a branch of the trigeminal nerve, supplies both the tip of the nose and the internal structures of the eye. A lesion here indicates the nerve branch to the eye is affected, increasing the likelihood of ocular involvement.
Diagnosis and Immediate Treatment
An ophthalmologist diagnoses herpes zoster cornea based on the characteristic shingles rash on the forehead and evidence of eye involvement. A primary diagnostic tool is the slit-lamp exam. This microscope gives the doctor a magnified view of the eye’s structures, like the cornea and iris, to assess for damage.
The goal of immediate treatment is to stop the virus from replicating and to control inflammation to prevent long-term damage. This is accomplished with high-dose oral antiviral medications, such as acyclovir, valacyclovir, or famciclovir. Starting this medication early can reduce the severity of symptoms and lower the risk of serious eye complications.
Alongside antiviral therapy, corticosteroid eye drops are frequently prescribed to reduce severe inflammation within the eye. These drops help prevent corneal scarring and control uveitis, a painful inflammation of the iris. Doctors may also use eye drops that keep the pupil dilated to alleviate pain and prevent complications like a spike in eye pressure.
Long-Term Corneal Health Risks
Even after the initial infection is controlled, herpes zoster ophthalmicus can leave lasting damage. One of the most significant risks is corneal scarring. Inflammation during the acute phase can cause the cornea to become scarred and swollen, which can permanently impair vision. Severe cases may require a corneal transplant.
Another serious complication is neurotrophic keratitis. The viral infection can damage the nerves that supply the cornea, reducing its sensation. A numb cornea is vulnerable to injury because the person cannot feel irritation or foreign objects, which can lead to persistent ulcers, thinning, or perforation of the cornea.
Chronic inflammation is another potential long-term issue. The virus can trigger an ongoing inflammatory response that persists for months or years, which can lead to secondary glaucoma. This occurs when inflammation disrupts the eye’s fluid drainage system, causing an increase in intraocular pressure that can damage the optic nerve.
Prevention Through Vaccination
The most effective prevention for herpes zoster cornea is vaccination against shingles. The shingles vaccine works by boosting the body’s specific immunity to the varicella-zoster virus. This enhanced immune response helps keep the dormant virus in its latent state, making reactivation much less likely.
For eligible individuals, typically adults aged 50 and older, the recombinant zoster vaccine is recommended. By preventing the reactivation of the virus, the vaccine protects against the development of shingles and its associated complications, including sight-threatening eye involvement.